Typically, graft copolymers of olefin polymer materials have been impact modified with ethylene/propylene copolymer rubber, ethylene/propylene/diene monomer rubber, and ASA polymers. For example, U.S. Pat. No. 3,314,904 describes forming a "gum plastic" by making a graft copolymer of styrene on polyethylene or polypropylene, and, in particular, a graft interpolymer of styrene, acrylonitrile, and polyethylene or polypropylene, and blending the graft copolymer with certain selected compatible rubbery materials. The grafted styrene or styrene/acrylonitrile content of the graft copolymer is 75-95% preferably 85-95%, and more preferably 90-95%. Hence the graft copolymer is predominantly bound styrene or bound styrene/acrylonitrile, and in the graft copolymers made from polypropylene, the polypropylene is only a minor component and present as a dispersed phase. Thus the properties of the bound styrene or styrene/acrylonitrile predominate. The graft copolymer is made by subjecting the polyolefin to high-energy ionizing radiation, and then contacting the irradiated polyolefin with styrene or with styrene and acrylonitrile.
U.S. Pat. No. 4,537,933 discloses a blend of a polyolefin graft polymer, preferably a polyvinyl halide polyolefin graft polymer, and an ASA polymer. The ASA polymer is a copolymer of styrene and acrylonitrile (SAN) that is modified with an acrylate polymer, a chlorinated polyethylene or an olefin-diolefin modified polymer, such as an ethylene/propylene polyene modified polymer. The ASA polymer modified with the olefin-diolefin modified polymer has a styrene/acrylonitrile content of 60-95%. The properties of the SAN predominate since the rubber is only a minor component and present as a dispersed phase. Also, the matrix phase of the polymeric components must be miscible.